1. Field of the Invention
This invention relates to a covering device for rotating parts, such as a safety cover and a guide, in a rotary press.
2. Description of the Related Art
As shown in FIG. 6, a web rotary press is generally configured as follows: In order to prevent something from being caught (so-called a wrap-in) into an area defined between and opposed to a plate cylinder 100 and a blanket cylinder 101 of a printing unit, a safety bar 102 extends along an axial direction of a cylinder shaft at a position upstream of the cylinders in the direction of cylinder rotation. In order to prevent ink scatter from around an area defined between and opposed to an ink form roller 103 and a rider roller 104 of ink rollers, a cover 105 is disposed at a position below these rollers 103 and 104 (upstream of these rollers in the direction of roller rotation) (see Japanese Utility Model Registration No. 2525261, FIGS. 1 and 2).
Because of the functions of the above-mentioned safety bar 102 and cover 105, the clearances between the safety bar 102 and the circumferential surfaces of the cylinders, and the clearances between the cover 105 and the circumferential surfaces of the rollers are narrow. While the cylinders 100 and 101 are rotating in the directions of arrows in FIG. 6, air is engulfed from the narrow clearances into a region surrounded by the circumferential surfaces of the cylinders and the safety bar 102 (the region indicated by a hatching in FIG. 6). While the rollers 103 and 104 are rotating in the directions of arrows in FIG. 6, air is engulfed from the narrow clearances into a region surrounded by the circumferential surfaces of the rollers and the cover 105 (the region indicated by a hatching in FIG. 6).
The air engulfed into any such region cannot escape through the narrow clearances to the outside, and builds up in each region, with its temperature rising in accordance with the rotations of the cylinders 100 and 101 and the rollers 103 and 104. As a result, a temperature difference emerges between the interior of the above region and the outside air, and dew forms on the surfaces of the safety bar 102 and the cover 105 located near those regions. Eventually, water droplets, which have fallen, adhere to printing products, causing a printing failure.